It shows a huge amount of giant spider crabs piling on top of one another.

The crustaceans are said to have come from the deep sea of the Bass Strait to the sheltered waters of Port Phillip Bay, in Melbourne, Australia.

This extraordinary natural spectacle is said to occur every winter in Australia.

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The annual event is thought to help protect the crabs from predatorsCredit: YouTube / Museums Victoria

However, similar events have been observed in different waters across the world.

It's thought that the crabs meet on mass to moult their shells in an attempt to be protected from predators.

This is because a crab that's just moulted it shell becomes soft and vulnerable until it's new outer shell forms.

When thousands of the crabs meet they end up creating piles that can be multiple crabs deep.

The crabs lower down will be more protected from predators like octopus and seagulls.

What are the most poisonous animals in the world?

Here are seven of the most deadly creatures...

The box jellyfish is widely regarded to be the most posionous animal in the world and contians a toxin that can cause heart attacks

Cobras, typically found in the jungles of India and China, can spit a venom which can result in death in a very short space of time and just 7ml of their venom is enough to kill 20 humans

The marbled cone snail is a sea creature that can release venom so toxic it can result in vision loss, respiratory failure, muscle paralysis and eventually death and, to make things worse, there is no anti-venom avaliable

Posion dart frogs are small and brightly coloured but have glands containing a toxin that blocks nerve signals to muscles, causing paralysis and death

Puffer fish are considered to be a dangerous delicacy because some of their anatomy contains a hazardous toxin which, if ingested in a large quantity, can cause convulsions, paralysis, cardiac arrhythmia, and ultimately death

The Brazillian wandering spider, also known as the 'banana spider', has venom that is so high in serotonin it can paralyse and kill

Death stalker scorpions have a fitting name as enough venom from one can cause a lot of pain and respiratory failure

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